JPS60230554A - Knocking suppressor for engine - Google Patents

Abstract

PURPOSE:To perform the suppression of knocking so effectively, by installing a water injection valve, feeding an antiknock of water or the like, in a suction passage, while controlling this valve so as to finish its injection feed of the antiknock at the first half part of a valve opening period in a suction valve at latest in a knocking generating region. CONSTITUTION:In case of a device which sets up a fuel injection valve 11 toward a suction valve, in a part at the downstream side of a throttle valve in a suction passage 5, a water injection valve 13 is set up toward the suction valve 3 in the suction passage 5 at the more upstream side than the fuel injection valve 11, causing it to spray and feed an antiknock of water or the like from the valve 13. The suction passage 5 is made up of both suction passages 5a and 5b at primary and secondary sides partitioned off by a partition wall 18, while a swirl control valve 15 is interposingly installed in the secondary side suction passage 5b. And, the water injection valve 13 is controlled so as to finish its injection feed of the antiknock of water or the like at the first half part of a valve opening period at latest in time of knocking occurrence or in a knocking occurring region.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an engine knock suppression device that suppresses the occurrence of knocking by injecting and supplying an anti-knock agent such as water into a combustion chamber. It is.

(Prior art) Conventionally, in order to suppress engine knocking, water or an aqueous solution containing an anti-knock agent is mixed with fuel and supplied to the engine when the engine is running at low, medium speeds and under high load to avoid the occurrence of knocking. For example, the technology to
It is known as seen in No.-50769.

However, when suppressing knocking by supplying an anti-knock agent such as water, supplying a large amount of anti-knock agent such as water may cause rust in the intake system or combustion chamber, and may cause anti-knock agents such as water to enter the lubricating oil. This has problems that adversely affect the durability and driving performance of the engine, such as deterioration due to mixing of knock agents and a decrease in output due to deterioration of combustibility. Therefore, it is best to suppress knocking with as little amount of anti-knock agent as possible, such as water. preferable.

On the other hand, in the combustion chamber of an engine, the end gas zone near the piston and away from the ignition plug is a part where knocking is likely to occur.

In order to suppress knocking by supplying an anti-knock agent such as water to this engine, for example, as in the prior art described above, the anti-knock agent such as water is supplied into the combustion chamber from the venturi of the carburetor through the intake passage. In such a case, the anti-knock agent such as water is uniformly distributed within the combustion chamber, and unless a large amount of anti-knock agent such as water is supplied, knocking in the above-mentioned knocking generating part cannot be effectively suppressed. However, the above-mentioned problems arise due to the supply of a large amount of anti-knock agent such as water.

(Object of the Invention) In view of the above circumstances, an object of the present invention is to provide an engine knock suppression device that effectively suppresses knocking by supplying a small amount of anti-knock agent such as water. be.

(Structure of the Invention) The knock suppressing device of the present invention is provided with a water injection valve that supplies an anti-knock agent such as water into the intake passage leading to the combustion chamber via the intake valve, and from the water injection valve to the intake valve at the latest. The present invention is characterized in that it includes a control device that controls the injection supply of the anti-knock agent such as water to end in the first half of the opening period.

(Effects of the Invention) According to the present invention, when knocking occurs or in a region where knocking occurs, the water injection timing is adjusted so that the injection supply of anti-knock agent such as water from the water injection valve ends in the first half of the intake valve open period at the latest. By setting this, the anti-knock agent such as water that flows into the early part of the intake stroke can be unevenly distributed and supplied to the lower part of the combustion chamber. By having an anti-knock agent present, a good knocking suppression effect can be obtained in this part, and knocking can be efficiently suppressed by supplying a small amount of anti-knock agent such as water, and a large amount of anti-knock agent such as water can be supplied. The accompanying adverse effects can be prevented.

In particular, as mentioned above, in order to make anti-knock agents such as water unevenly distributed in the lower part of the combustion chamber, the presence of anti-knock agents such as water in combustion parts such as near the spark plug decreases, which reduces combustibility. It maintains good combustibility without causing any negative effects, reduces output loss, and suppresses the occurrence of knocking, making it possible, for example, to advance the ignition timing and improve output. .

(Example) Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows the overall components of an engine equipped with a knock suppressor.
However, only one cylinder is shown in the diagram)
An intake passage 5 and an exhaust passage 6 are connected to the combustion chamber 2 of each cylinder C via an intake valve 3 and an exhaust valve 4, respectively. A throttle valve 8 is provided, an air cleaner 9 is connected to the upstream end of the intake passage 5, and an air flow meter 10 for measuring the intake air flow is provided downstream of the air cleaner 9. A fuel injection valve 11 is disposed in a downstream portion of each intake passage 5 facing the intake valve 3, and a fuel supply passage 12 is connected to each fuel injection valve 11 via a regulator (not shown). The fuel injection valve 11 is connected to a fuel tank, and fuel pressure is supplied to the fuel injection valve 11 via the regulator so that the differential pressure with the intake passage pressure is always constant.

In addition, water injection valves 13 are respectively disposed in the intake passages 5 on the upstream side of each fuel injection valve 11, facing the intake valves 3.
A water supply passage 14 is connected to each water injection valve 13, and is configured to inject and supply an anti-knock agent such as water to the combustion chamber 2.

On the other hand, the intake passage 5 is connected to the cylinder C constituting the combustion chamber 2.
The intake passage 5 is configured to generate a swirl in the circumferential direction, and a swirl control valve 15 is disposed in the intake passage 5 to control the magnitude of the swirl.

As shown in FIG. 2, the intake passage 5 is a downstream portion of the intake passage 5 that communicates with the combustion chamber 2, and a portion near the combustion chamber 2 formed in the cylinder head 17 from the intake manifold 16 is a partition wall. 18, it is divided into a primary side intake passage 5a and a secondary side intake passage 5b, and a swirl control valve 15 is interposed in the secondary side intake passage 5b, and this swirl control valve 15 is connected to an actuator (not shown). ) basically corresponds to the increase or decrease in intake air, and is configured to be closed when the engine is under low load, and open when the engine is under high load to supply intake air from the secondary intake passage 5b.

The primary side intake passage 5a is formed with a relatively small passage area, and opens as a swirl port 19a at the intake port 19 slightly upstream of the intake valve 3.
The swirl port 19a opens toward the circumferential direction of the cylinder C to flow the intake air from the side in a circular direction into the cylinder C so that the angle with the top surface of the piston 20 becomes small. It is configured to be introduced in the circumferential direction to generate a swirl. On the other hand, the secondary intake passage 5b opens in a direction substantially parallel to the center line of the cylinder C, that is, toward the upper surface of the piston 20, and is configured to introduce intake air without swirling.

Therefore, when the swirl control valve 15 is closed and the opening degree is 0', intake air is introduced into the combustion chamber 2 in a large swirl only by the primary side intake passage 5a, and as the swirl control valve 15 opens, the intake air is introduced into the combustion chamber 2 with a large swirl. The introduction ratio of intake air from the intake passage 5b increases, the swirl generated in the combustion chamber-2 becomes smaller, and the swirl control valve 15 is fully open (70 degrees of opening).
In this case, almost no swirl is generated.

This swirl control valve 15 is mechanically controlled to open and close by an actuator (not shown), for example, by a diaphragm device that responds to intake negative pressure or exhaust pressure.

The swirl control valve 15 responds to fluctuations in the intake atmosphere, that is, the engine rotation speed and load, by setting the opening degree to 06 (fully open) in the low load/low rotation range, for example, and generates a large swirl. In the high rotation range, the opening degree is set to 70.
degree (fully open) to suppress the generation of swirl, and in the intermediate region, the opening degree is slightly opened to 20 degrees to generate a weak swirl.

Furthermore, on the downstream side of the swirl control valve 15 in the secondary intake passage 5b, there is a position relatively close to the intake port 19 that is opened and closed by the intake valve 3, and injects fuel toward the combustion chamber 2. The water injection valve 13 and the fuel injection valve 11 are arranged in this order. That is, the anti-knock agent such as water and fuel injected from the water injection valve 13 and the fuel injection valve 11 directly flow into the combustion chamber 2 from the intake port 19.

The injection timing of the antiknock agent such as water, the fuel injection timing, and the injection port by the water injection valve 13 and the fuel injection valve 11 are controlled by control signals from the control device 22, that is, the water injection pulse and the fuel injection timing, as shown in FIG. This is done by injection pulses.

This control device 22 includes an interface 24, a CPU 2
5 and a memory 26, and the memory 26 stores programs for arithmetic processing of the CPU 25 as shown in the flowchart of FIG. In addition, this control device 22
In addition to inputting the intake air amount signal from the air flow meter 10, the knocking signal from the knock sensor 27, which detects the occurrence of knocking in each cylinder of the engine using a vibration sensor, etc., and the rotation angle of the distributor are used to detect the engine. 1 and a crank angle signal from a crank angle sensor 28 for detecting the piston top dead center TDC of the first cylinder are respectively inputted. Note that 29 is an ignition switch.

Then, the CPU 25 of the control device 22 receives the knocking detection signal from the knock sensor 27, sets a predetermined water injection timing in the water injection valve 13 for the cylinder in which knocking is occurring, and adjusts the timing accordingly. A water injection pulse having a pulse width corresponding to the injection DI amount of anti-knock agent such as water is output to the water injection valve 13 of the corresponding cylinder.

The injection timing of the anti-knock agent such as water from the water injection valve 13 is set so that the injection ends at the latest in the first half of the intake stroke when the intake valve 3 is open, so that the injected anti-knock agent such as water It is supplied so as to be unevenly distributed in the end gas zone around the piston 20 in the lower part of the combustion chamber 2.

In addition, the CPLI 25 calculates the basic fuel injection amount according to the engine speed and intake air teeth, and increases this basic fuel injection amount when the engine is cold or when accelerating to determine the actual fuel injection amount. Melt.

At least when the engine is under low load, the fuel necessary for one combustion is injected and supplied from the fuel injection valve 11 during the open period of the intake valve 3 and at a predetermined time after the intake valve 3 is opened, thereby performing stratified combustion. The fuel injection timing is set according to the fuel injection timing, and a fuel injection pulse having a pulse width corresponding to the fuel injection amount is output to the fuel injection valve 11 of each cylinder at a predetermined timing.

The water injection timing for unevenly supplying the anti-knock agent such as water is, as shown in FIG.
During the intake stroke from when the intake valve 3 closes after bottom dead center BDC to IC, the injection of anti-knock agent such as water starts from the water injection start time θl immediately after the opening time IO of the intake valve 3. Injection is started and ends at water injection end time θ2 after a period for obtaining a predetermined amount of injection, and this water injection end time θ2 is set at an early time before the first half of the intake stroke at the latest. be.

As a result, the anti-knock agent such as water flows into the combustion chamber 2 in the first half of the intake period when the intake valve 3 is open, and is supplied unevenly to the lower part of the combustion chamber 2. The generated swirl suppresses vertical diffusion.

Furthermore, in FIG. 3, the fuel injection timing for performing stratified combustion is such that fuel injection ends in the latter half of the intake stroke when the intake valve 3 is open, that is, at a predetermined period earlier than the closing timing IC of the intake valve 3. J: Uni, a fuel injection end time θ4 is set, and a fuel injection start time θ3 is set at a time that is one period θ corresponding to the pulse width corresponding to the fuel injection amount with respect to this fuel injection end time θ4. It is.

As a result, fuel flows into the combustion chamber 2 at a relatively late stage during the intake period when the intake valve 3 is open, and the fuel flows into the upper layer of the combustion chamber 2 without being mixed with the anti-knock agent such as water from the water injection valve 13. Moreover, the swirl in the circumferential direction suppresses vertical diffusion and maintains this stratification. The stratified combustion described above secures the air-fuel ratio necessary for ignition near the spark plug by unevenly distributing fuel in the upper layer of the combustion chamber 2, and obtains good combustibility even with a very lean mixture in the lower layer. As a result, the air-fuel ratio as a whole can be made leaner, improving fuel efficiency, and the emission of unburned components can be suppressed, thereby improving emissions. Note that if the fuel is injected and supplied in the latter half of the intake stroke, especially just before the intake valve 3 closes, the above uneven distribution of fuel, that is, stratification, can be reliably achieved, but in this case, the vaporization and atomization of the fuel are Since fuel that has not progressed much will flow in, within the range where stratification can be maintained well by large swirls, the piston speed will be large and the suction speed will be high, promoting atomization of the fuel and improving combustibility. In order to improve the performance, it is preferable to advance the injection end timing to the middle side of the intake stroke rather than the latter half of the intake stroke in a region where an anti-knock agent such as water is not supplied.

By unevenly distributing the injection supply of the anti-knock agent such as water as described above, knocking is suppressed without adversely affecting the combustibility of the fuel, and the torque at the knocking limit is improved. In other words, the torque gradually increases as the ignition timing is advanced, but once the ignition timing is advanced to the knocking limit, if the ignition timing is advanced any further, knocking will occur and abnormal combustion will occur. This adversely affects engine vibration and durability, and it is not possible to improve torque by advancing the ignition timing beyond this knocking limit. However, if the knocking limit is increased by supplying an anti-knock agent such as water without reducing combustibility to prevent the occurrence of knocking, knocking will not occur even if the ignition timing is advanced beyond the knocking limit. This does not occur, and as the ignition timing advances, greater torque is obtained. In particular, when injected fuel is stratified, the end gas zone around the piston becomes extremely lean due to this stratification, which further suppresses the occurrence of knocking. The number of knock agent supply ports is reduced.

Next, the operation of the control device 22 will be explained with reference to the flowchart shown in FIG.

When the engine operates, the CPU 25 controls the crank angle sensor 28, the air flow meter 10, and the knock sensor 27.
Each signal is read and stored in registers T, A, and K (steps 81 to 83). Next, step S4
It is determined whether or not knocking is occurring in any cylinder of the engine, and when knocking occurs, C'PU25
is determined to be YES in step S4, and the process proceeds to step S5.
Then, the water injection start timing θ1 and the water injection end timing θ2 of the anti-knock agent such as water are calculated and determined from the map. In this map, the water injection end timing θ2 is set before the first half of the intake stroke in any cylinder.

When the water injection start time θl and the water injection end time θ2 are determined in step S5, the process waits in step S6 until the water injection start time θl is reached, and when the water injection start time θ1 is reached, the water injection valve 13 is activated in step S7. 11111 signal is applied to the water injection valve 13, the system waits in step S8 while continuing to drive the water injection valve 13, and when the water injection end time θ2 is reached, the output of the l T I+ signal is stopped (step S9), and the water injection pulse is added as described above. After the injection supply of the anti-knock agent such as water is finished, and when knocking is not occurring, a negative determination is made in step S4 and the process proceeds to step S10 without injecting the anti-knock agent such as water.

In step S10, the engine speed is calculated using the crank angle in the register T, and it is stored in the register N.
Next, calculate the fuel injection return using the engine speed and intake air in registers N and A, and make acceleration corrections as necessary.
Perform temperature correction and store the actual injection amount in the register Q (step 811), determine the injection angle θ for one intake stroke from the actual fuel injection amount in the register Q, and store it in the register θ (step 811). 512).

Next, in step 813, fuel injection start timing θ3 and fuel injection end timing θ4 are determined. This fuel injection start timing θ
3 and the fuel injection end time θ4 are determined by first calculating the fuel injection end time θ4 from the map, and based on this fuel injection end time θ4, the fuel injection start time θ3 is determined according to the actual injection amount θ in the register θ. It is up to you to decide. In addition,
The optimal fuel injection timing is set in the above map in order to obtain stratified charge combustion in accordance with each operating state.

In this way, the fuel injection start timing θ3 and the fuel injection end timing θ4 are determined.
The process waits in step S14 until the fuel injection start time θ3 is reached, and the fuel injection valve 11 is set to 1 in step S15.
'' signal is applied, and the fuel injection valve 11 is continued to be driven while waiting in step S16, and when the fuel injection end time θ4 is reached, the output of the ``'1'' signal is stopped (step 517), and a fuel injection pulse is applied as described above. After that, the process returns to step S1.

According to the embodiments described above, when knocking occurs, anti-knock agent such as water is unevenly distributed and injected into the lower part of the combustion chamber 2 from the water injection valve 13, and the water or other anti-knock agent is supplied to the lower part of the combustion chamber 2 until the occurrence of knocking is eliminated. In addition to injecting and supplying an anti-knock agent, stratified combustion is performed by unevenly distributing fuel to improve fuel efficiency and combustion efficiency.At the same time, the air-fuel ratio in the end gas zone near the piston is lean to make ignition difficult and prevent knocking. By obtaining a suppressing effect, the occurrence of knocking can be efficiently suppressed using an anti-knocking agent such as water, and as a result, the output can be improved.

In the above embodiment, when knocking occurs and the water injection valve 13 is injecting an anti-knock agent such as water, the swirl control valve 15 is controlled in a direction to strengthen the swirl, and a large swirl is generated. It is preferable to increase the effect of maintaining the uneven distribution of anti-knock agents such as water.

Further, in the above embodiment, the occurrence of knocking is detected using the knock sensor 27, and in response to this, when knocking occurs, an anti-knock agent such as water is injected and supplied to suppress the knocking that is actually occurring. In addition to this, an anti-knock agent such as water is always applied to the water injection valve 13 in a knocking generation area, that is, an operating area where knocking is likely to occur, for example, during high load and low rotation.
In order to avoid the occurrence of knocking by injecting water from It may also be configured to be controlled by the control device 22 so as to output the injection pulse.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram of an engine equipped with a knock suppression device according to an embodiment of the present invention, Fig. 2 is a vertical cross-sectional view of main parts showing a specific structural example of the engine, and Fig. 3 is a diagram showing water flow during the intake stroke. FIG. 4 is a timing diagram showing the injection timing of the anti-knock agent and the fuel injection timing. FIG. 4 is a flowchart showing the processing of the control device. 1...Engine 2...Combustion chamber 3...
... Intake valve 5 ... Intake passage 11 ...
・・Fuel injection valve 13・Old・・Water injection valve 22・・・・
・Control device 24...Crank angle sensor

Claims (1)

[Claims] (1) A water injection valve is provided for each cylinder of the engine to supply an anti-knock agent such as water into the intake passage leading to the cooking chamber via the intake valve, and when knocking occurs or in the area where knocking occurs, the water injection valve 1. A knock suppressing device for an engine, comprising a control device that controls the injection supply of an anti-knock agent such as water to end in the first half of the opening period of an intake valve at the latest.